The objective of this proposal is to characterize hexose transport in Chinese hamster ovary cells in culture utilizing the techniques of biochemistry and genetics. Employing a rapid kinetic transport assay, uptake of 3-O-methylglucose, a non-metabolizable sugar and D-glucose in ATP-depleted cells will be followed. Uptake under these conditions can be clearly ascribed to transport rather than metabolism. Three independent methods for isolating hexose transport mutants have been proposed: resistance to killing by glucose analogues, resistane to killing by tritium suicide, and resistance to killing by inhibitors of glucose transport.